Coolant circuit for controlling the temperature of a cooling fluid and motor vehicle therewith

ABSTRACT

The invention relates to a coolant circuit ( 5, 6, 7, 7   a,    8, 8   a ), preferably for cooling a drive or an engine ( 2 ) of a motor vehicle ( 1 ), in particular of a passenger car, comprising: a controller ( 8 ) which, in order to control the temperature of a cooling fluid ( 7   a ), activates an electrically operated fan motor ( 5 ). The controller ( 8 ) is in thermal contact with the cooling fluid ( 7   a ) in order to be cooled and is formed to detect the temperature of the cooling fluid ( 7   a ) by way of a temperature sensor ( 8   a ) which is preferably provided at the controller ( 8 ). A defined temperature of the cooling fluid ( 7   a ) can thereby be set without a control signal from a master control or regulating device being required for this purpose.

The invention relates to a coolant circuit, preferably for cooling a drive or an engine of a motor vehicle, in particular of a passenger car, comprising: a controller which, in order to control the temperature of a cooling fluid, activates an electrically operated fan motor which serves to extract heat from the cooling fluid, whereby the controller determines the voltage of the fan motor. The fan motor of the coolant circuit is driven either electrically or mechanically when the engine is running. When the engine is stopped, afterrunning of the fan motor, which is then electrically operated, normally occurs at the relevant engine temperature. It is usual to use water as the cooling fluid in a coolant circuit of this kind. It is understood that a coolant circuit of this kind can be used not only to cool an (internal combustion) engine, but also to cool other drives, e.g. to cool fuel cells.

The fan has an electric motor whose power can in most cases be gradually controlled. In practice the power control takes place with parallel or serial switches or relays. Continuous control with controllers based on pulse-width modulation, so-called PWM controllers, is also known where vehicles of the top category are concerned. The PWM controllers accordingly function in the engine compartment with its frequently very high temperatures.

It is known to provide a temperature sensor in the coolant circuit for determining the temperature of the cooling fluid, which sensor is connected to a control unit outside of the coolant circuit. The control unit evaluates the signal of the temperature sensor and passes on information concerning the coolant temperature to the controller. A considerable expenditure on cabling is necessary to connect the control unit to the controller or the temperature sensor.

The object of the invention is to provide a coolant circuit, a motor vehicle with a coolant circuit of this kind, a coolant conduit, a cooler and a CRFM module with a cooler of this kind which enable the temperature of the cooling fluid and therefore the temperature of a device which is to be cooled, e.g. of an internal combustion engine, to be controlled in a simple and inexpensive manner.

This object is solved by the features of the independent claims. Advantageous developments and further embodiments will emerge from the features of the dependent claims.

According to one aspect, the object is solved by a coolant circuit of the type initially mentioned in which the controller is in thermal contact with the cooling fluid in order to be cooled, and in which the controller is formed to detect the temperature of the cooling fluid by means of a temperature sensor which is preferably provided at the controller. The controller compares the detected (actual) temperature with an ideal temperature of the cooling water and activates the fan motor in order to regulate the temperature of the cooling water to the ideal temperature or to set an upper limit to this.

The temperature of the cooling fluid can be set independently of a master control or regulating device, as the temperature control is carried out directly by the actual controller. The fact that the controller is indirectly or directly in thermal contact with the cooling fluid for the purpose of its cooling can be utilised in this connection. The temperature sensor can therefore in particular form a unit with the controller, i.e. be integrated into the latter or fastened to it, so that only a single subassembly is required for controlling the temperature of the fan motor, which further reduces the expenditure on cabling.

The coolant circuit can therefore be used as an independent unit for controlling the temperature of the cooling fluid. Only the ideal temperature of the cooling fluid or of the internal combustion engine which is to be cooled is optionally still predetermined by an external control device.

In a preferred embodiment the controller is formed as an (analogue) linear controller. In the case of a motor vehicle with a continuously controllable fan motor the provision of a linear controller enables the motor to be controlled with good electromagnetic compatibility at low costs. In the first place the continuous controllability results in minimal noise generation with a minimal load on the battery. When compared with a control with a relay, there is greater reliability due to fewer electrical connections and fewer cables and, due to the presence of an overheating protection system, fewer failures with a lower fire risk. The use of a linear controller instead of a relay also results in a weight reduction of approximately 50% with an at least 80% smaller space requirement at less than half the price. Furthermore, the assembly costs are lower and diagnosis in the event of a fault can be carried out.

When compared with PWM controllers, the linear controller has distinctly better electromagnetic compatibility, as the former are pulsed at 20 kHz in a disadvantageous manner. The PWM controller therefore requires extensive measures for guaranteeing electromagnetic compatibility, which makes the PWM controller a component which today is approximately three times as expensive as a linear controller. For the first time the solution enables the engine fan in small and medium-sized category vehicles to be continuously controlled at acceptable prices, although on the other hand requires intervention in the complex cooling system of the internal combustion engine by removing the dissipated power of the controller to the water circuit.

In one embodiment the controller is in thermal contact with a coolant conduit of the coolant circuit. This enables a position of the controller close to the fan motor to be selected when the vehicle is designed in order thereby to reduce the cabling expenditure.

In a further embodiment the coolant conduit has a recess in which the controller or a cooling block associated with the controller is partly set. The coolant conduit consists, for example, of diecast aluminium, in the recess of which the controller or its cooling block is set and appropriately sealed. The controller is therefore thermally coupled to the cooling fluid of the coolant circuit, which is more efficient than cooling via the medium air. The temperature sensor is in this case either directly in contact with the cooling fluid or formed to measure the temperature of the cooling block, from which the controller establishes the temperature of the cooling fluid.

In a further embodiment the controller is in thermal contact with a cooler which is associated with the coolant circuit and contains the cooling fluid. The controller can in this case lie directly on the (water) cooler, with the temperature sensor measuring the temperature of the cooler housing, from which the controller in turn determines the temperature of the coolant. It is understood that the controller can in this case be disposed in the vicinity of the coolant entrance of the cooling fluid into the cooler in order to establish the temperature of the cooling fluid which is heated by the internal combustion engine or to regulate it to an ideal temperature, or at a coolant outlet in order to detect the temperature of the cooling fluid cooled by the cooler and to control it.

A further aspect of the invention relates to a motor vehicle for a coolant circuit as described above for cooling an internal combustion engine. As already indicated, the cabling expenditure can be reduced in a motor vehicle of this kind.

One aspect of the invention relates to a coolant conduit for a coolant circuit of a motor vehicle which comprises a controller, in particular a linear controller, with a temperature sensor for determining the temperature of a cooling fluid flowing through the coolant conduit during operation. As mentioned above, the distance between the controller and the fan motor and therefore the cable length of a control line from the controller to the fan motor can as a result be kept small.

In one embodiment the coolant conduit comprises a recess in which the controller or a cooling block associated with the controller is partly set, so that the controller is thermally coupled to the cooling fluid of the water circuit in a particularly favourable manner.

A further aspect of the invention relates to a cooler for a coolant circuit of a motor vehicle which comprises a controller, in particular a linear controller, connected thereto in a detachable manner, with a temperature sensor for determining the temperature of a cooling fluid flowing through the cooler during operation. The (water) cooler can be prepared in so far as the controller is set in the cooler or fastened to the latter by way of a clip connection. The controller can be mounted on one of the lateral coolant end tanks of the cooler. In this connection the end tank which is on the coolant outlet side is preferably selected on account of the lower temperatures of the coolant. Due to a combined cooler/controller, the process of assembling the components in the engine compartment becomes easier, the assembly time is reduced, the components can be disposed in a more compact manner and this results in greater freedom in the development of a new vehicle.

A further aspect of the invention relates to a CRFM module with a fan motor and a cooler as described above. Here too, due to the integration of functions undertaken, there is a lower space requirement for the components in the engine compartment with greater freedom in the development of a new vehicle.

Embodiments of the invention are represented in the schematic drawings and illustrated in the following description. In the drawings:

FIG. 1 shows a motor vehicle in a plan view,

FIG. 2 shows a water cooler in a side view, and

FIG. 3 shows a coolant conduit with a set-in linear controller.

In the figures, in which the same objects are generally marked with the same reference characters, FIG. 1 shows a motor vehicle 1 in a plan view. The motor vehicle 1 has an internal combustion engine 2, upstream of which a water cooler 3 and an air conditioning condenser 4 are disposed. A fan motor 5 is provided for afterrunning of the cooler after the motor vehicle 1 has been stopped.

The water cooler 3, the air conditioning condenser 4 and the fan motor 5 can be individual components for the separate cooling circuits or component parts of a CRFM module (condenser radiator fan module) 6, as indicated by the broken line. The CRFM module 6 cools the internal combustion engine 2 in a known manner by way of a coolant conduit 7 with water as the cooling fluid 7 a.

A controller 8, which is formed as a linear controller, is set in the coolant conduit 7. The controller 8 is connected via an electric line 9 to the CRFM module and continuously controls the fan or fan motor 5 thereof. The fan noise upon afterrunning and also the load on the battery (not shown) are as a result reduced to a minimum with low costs and in an electromagnetically compatible manner. This succeeds in spite of the occasionally high temperatures in the engine compartment with the controller 8, which can be adequately cooled by the cooling fluid in the water circuit.

The controller 8 also comprises a temperature sensor 8 a which is directly in thermal contact with the cooling fluid 7 a. The signal which is delivered by the temperature sensor 8 a and which corresponds to the actual temperature of the cooling fluid 7 a is evaluated by the controller 8 and this activates the fan motor 5 via the line 9 such that a desired ideal temperature of the cooling fluid 7 a is obtained. The coolant circuit of the motor vehicle 1 therefore represents a closed-loop control system which can control the temperature of the cooling fluid 7 a and therefore of the internal combustion engine 2 without an external control device. Only the ideal temperature of the cooling fluid can optionally be predetermined by an external control device.

FIG. 2 shows the water cooler 3 in which the linear controller 8 is tightly screwed onto an end tank 12. As the coolant entrance 13 is on the right and the coolant outlet 14 on the left in FIG. 2, the end tank 12 on the coolant outlet side is selected on account of the lower temperatures. The water cooler 3 has a depression (not shown) which is adapted to the dimensions of the linear controller 8 and partly accommodates the linear controller. The water cooler 3 can be part of the CRFM module 6 of FIG. 1. The controller 8 comprises a temperature sensor 8 a which is in thermal contact with the end tank 12 and indirectly detects the temperature of the cooling fluid via the temperature of the end tank 12 in thermal contact with the cooling fluid.

FIG. 3 shows the coolant conduit 7 for the coolant circuit for the internal combustion engine 2. This has a recess 10 in which a cooling block 11 of the linear controller 8 is set so that cooling fluid of the coolant circuit flows directly around it.

The linear controller 8 comprises a temperature sensor (not shown) which is thermally connected to the cooling block 11, so that the controller 8 can detect the temperature of the cooling fluid in the coolant conduit 7 on the basis of the temperature of the cooling block 11.

Although specific embodiments have been described above, the person skilled in the art will recognise that the purpose of the description of these embodiments is not to restrict the invention in the presented form. The invention is on the contrary to comprise all modifications, equivalents and alternatives which fall within the protective scope of the claimed invention. The invention can in particular be used with all technical devices which comprise a fan motor for controlling the temperature of the cooling fluid of a coolant circuit. 

1. Coolant circuit (5, 6, 7, 7 a, 8, 8 a), preferably for cooling a drive or an engine (2) of a motor vehicle (1), in particular of a passenger car, comprising: a controller (8) which, in order to control the temperature of a cooling fluid (7 a), activates an electrically operated fan motor (5), characterised in that the controller (8) is in thermal contact with the cooling fluid (7 a) in order to be cooled, and that the controller (8) is formed to detect the temperature of the cooling fluid (7 a) by way of a temperature sensor (8 a) which is preferably provided at the controller (8).
 2. Coolant circuit according to claim 1, in which the controller (8) is a linear controller.
 3. Coolant circuit according to claim 1 or 2, in which the controller (8) is in thermal contact with a coolant conduit (7) of the coolant circuit.
 4. Coolant circuit according to claim 3, in which the coolant conduit (7) has a recess (10) in which the controller (8) or a cooling block (11) associated with the controller (8) is partly set.
 5. Coolant circuit according to any one of the preceding Claims, in which the controller (8) is in thermal contact with a cooler (3) for cooling the cooling fluid (7 a).
 6. Motor vehicle (1) with a coolant circuit (5, 6, 7, 7 a, 8, 8 a) according to any one of the preceding Claims for cooling its internal combustion engine (2).
 7. Coolant conduit (7) for a coolant circuit (5, 6, 7, 7 a, 8, 8 a) of a motor vehicle (1) which comprises a controller (8), in particular a linear controller, with a temperature sensor (8 a) for determining the temperature of a cooling fluid (7 a) flowing through the coolant conduit (3) during operation.
 8. Coolant conduit according to claim 7 which comprises a recess (10) in which the controller (8) or a cooling block (11) associated with the controller (8) is partly set.
 9. Cooler (3) for a coolant circuit (5, 6, 7, 7 a, 8, 8 a) of a motor vehicle (1) which comprises a controller (8), in particular a linear controller, connected thereto in a detachable manner, with a temperature sensor (8 a) for determining the temperature of a cooling fluid (7 a) flowing through the cooler (3) during operation.
 10. CRFM module (6), comprising a fan motor (5) and a cooler (3) according to claim
 9. 